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This work addresses the need for new chemical matter in product development for control of pest insects and vector-borne diseases. We present a barcoding strategy that enables phenotypic screens of blood-feeding insects against small molecules in microtiter plate-based arrays and apply this to discovery of novel systemic insecticides and compounds that block malaria parasite development in the mosquito vector. Encoding of the blood meals was achieved through recombinant DNA-tagged Asaia bacteria that successfully colonised Aedes and Anopheles mosquitoes. An arrayed screen of a collection of pesticides showed that chemical classes of avermectins, phenylpyrazoles, and neonicotinoids were enriched for compounds with systemic adulticide activity against Anopheles. Using a luminescent Plasmodium falciparum reporter strain, barcoded screens identified 48 drug-like transmission-blocking compounds from a 400-compound antimicrobial library. The approach significantly increases the throughput in phenotypic screening campaigns using adult insects and identifies novel candidate small molecules for disease control.
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Código de Barras del ADN Taxonómico/métodos , Evaluación Preclínica de Medicamentos/métodos , Malaria/prevención & control , Acetobacteraceae/genética , Animales , Anopheles/genética , Anopheles/microbiología , Antimaláricos/farmacología , Insecticidas , Malaria/parasitología , Malaria/transmisión , Mosquitos Vectores/microbiología , ARN Ribosómico 16S/genéticaRESUMEN
Mutations in the kelch propeller domain (K13 propeller) of Plasmodium falciparum parasites from Southeast Asia are associated with reduced susceptibility to artemisinin. We exposed in vitro-cultured stage V gametocytes from Cambodian K13 propeller mutant parasites to dihydroartemisinin and evaluated the inhibition of male gamete formation in an in vitro exflagellation inhibition assay (EIA). Gametocytes with the R539T and C580Y K13 propeller alleles were less susceptible to dihydroartemisinin and had significantly higher 50% inhibitory concentrations (IC50s) than did gametocytes with wild-type alleles.
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Antimaláricos/farmacología , Artemisininas/farmacología , Resistencia a Medicamentos/efectos de los fármacos , Plasmodium falciparum/efectos de los fármacos , Cambodia , Flagelos/efectos de los fármacos , Células Germinativas/efectos de los fármacos , Humanos , Concentración 50 Inhibidora , Malaria Falciparum/parasitología , Mutación , Plasmodium falciparum/genética , Plasmodium falciparum/aislamiento & purificación , Proteínas Protozoarias/genéticaRESUMEN
The 2-aminopyridine MMV048 was the first drug candidate inhibiting Plasmodium phosphatidylinositol 4-kinase (PI4K), a novel drug target for malaria, to enter clinical development. In an effort to identify the next generation of PI4K inhibitors, the series was optimized to improve properties such as solubility and antiplasmodial potency across the parasite life cycle, leading to the 2-aminopyrazine UCT943. The compound displayed higher asexual blood stage, transmission-blocking, and liver stage activities than MMV048 and was more potent against resistant Plasmodium falciparum and Plasmodium vivax clinical isolates. Excellent in vitro antiplasmodial activity translated into high efficacy in Plasmodium berghei and humanized P. falciparum NOD-scid IL-2Rγ null mouse models. The high passive permeability and high aqueous solubility of UCT943, combined with low to moderate in vivo intrinsic clearance, resulted in sustained exposure and high bioavailability in preclinical species. In addition, the predicted human dose for a curative single administration using monkey and dog pharmacokinetics was low, ranging from 50 to 80 mg. As a next-generation Plasmodium PI4K inhibitor, UCT943, based on the combined preclinical data, has the potential to form part of a single-exposure radical cure and prophylaxis (SERCaP) to treat, prevent, and block the transmission of malaria.
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Objectives: Novel chemical tools to eliminate malaria should ideally target both the asexual parasites and transmissible gametocytes. Several imidazopyridazines (IMPs) and 2-aminopyridines (2-APs) have been described as potent antimalarial candidates targeting lipid kinases. However, these have not been extensively explored for stage-specific inhibition of gametocytes in Plasmodium falciparum parasites. Here we provide an in-depth evaluation of the gametocytocidal activity of compounds from these chemotypes and identify novel starting points for dual-acting antimalarials. Methods: We evaluated compounds against P. falciparum gametocytes using several assay platforms for cross-validation and stringently identified hits that were further profiled for stage specificity, speed of action and ex vivo efficacy. Physicochemical feature extraction and chemogenomic fingerprinting were applied to explore the kinase inhibition susceptibility profile. Results: We identified 34 compounds with submicromolar activity against late stage gametocytes, validated across several assay platforms. Of these, 12 were potent at <100 nM (8 were IMPs and 4 were 2-APs) and were also active against early stage gametocytes and asexual parasites, with >1000-fold selectivity towards the parasite over mammalian cells. Front-runner compounds targeted mature gametocytes within 48 h and blocked transmission to mosquitoes. The resultant chemogenomic fingerprint of parasites treated with the lead compounds revealed the importance of targeting kinases in asexual parasites and gametocytes. Conclusions: This study encompasses an in-depth evaluation of the kinase inhibitor space for gametocytocidal activity. Potent lead compounds have enticing dual activities and highlight the importance of targeting the kinase superfamily in malaria elimination strategies.
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Aminopiridinas/farmacología , Antimaláricos/farmacología , Fosfotransferasas/antagonistas & inhibidores , Plasmodium falciparum/efectos de los fármacos , Plasmodium falciparum/enzimología , Inhibidores de Proteínas Quinasas/farmacología , Aminopiridinas/química , Aminopiridinas/aislamiento & purificación , Antimaláricos/química , Antimaláricos/aislamiento & purificación , Supervivencia Celular/efectos de los fármacos , Concentración 50 Inhibidora , Pruebas de Sensibilidad Parasitaria , Plasmodium falciparum/química , Inhibidores de Proteínas Quinasas/química , Inhibidores de Proteínas Quinasas/aislamiento & purificaciónRESUMEN
Most antimalarial drugs target asexual parasites without reducing gametocyte formation or development. Drugs with dual roles, i.e., those that can target both asexual parasites and gametocytes, would improve the control of malaria. In the current study, MEFAS, a hybrid drug derived from mefloquine and artesunate that has been shown to be an active blood schizonticidal drug, was assessed to determine its ability to block the infectivity of Plasmodium falciparum gametocytes. MEFAS was 280 and 15 times more effective than mefloquine alone and artesunate alone, respectively.
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Antimaláricos/farmacología , Artemisininas/farmacología , Mefloquina/farmacología , Plasmodium falciparum/efectos de los fármacos , Artesunato , Malaria Falciparum/parasitologíaRESUMEN
BACKGROUND: Drugs that kill or inhibit Plasmodium gametocytes in the human host could potentially synergize the impact of other chemotherapeutic interventions by blocking transmission. To develop such agents, reliable methods are needed to study the in vitro activity of compounds against gametocytes. This study describes a novel assay for characterizing the activity of anti-malarial drugs against the later stages of Plasmodium falciparum gametocyte development using real-time PCR (qPCR). METHODS: Genes previously reported to be transcribed at the different sexual stages of the gametocytogenesis were selected for study and their mRNA expression was measured in a gametocytogenesis course by qPCR. Genes mainly expressed in the later stages of gametocyte development were used as a surrogate measurement of drug activity. To distinguish between cidal and static drug effects, two different experiments were performed in parallel, one with constant drug pressure throughout the experiment (144 h), and another in which the gametocyte cultures were exposed to the compound for only 48 h. RESULTS: Four P. falciparum genes coding for proteins Pf77, ROM3, Pfs25, and Pfg377 with transcription specific for late-stage gametocyte development were identified. The in vitro anti-malarial activity of compounds against such gametocytes was assessed by measuring mRNA levels of these genes using qPCR. The assay was validated against standard anti-malarial drugs (epoxomicin, dihydroartemisinin, chloroquine, thiostrepton, and methylene blue) and compounds from the GSK compound library with known anti-gametocyte activity. CONCLUSIONS: This study describes a novel assay for characterizing the activity of anti-malarial drugs against the later stages of P. falciparum gametocyte development using qPCR in genetically unmodified parasites. The method described is a reliable and user-friendly technique with a medium throughput that could be easily implemented in any laboratory.
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Antimaláricos/aislamiento & purificación , Antimaláricos/farmacología , Descubrimiento de Drogas/métodos , Evaluación Preclínica de Medicamentos/métodos , Plasmodium falciparum/efectos de los fármacos , Reacción en Cadena en Tiempo Real de la Polimerasa/métodos , Supervivencia Celular/efectos de los fármacos , Perfilación de la Expresión Génica , Plasmodium falciparum/fisiologíaRESUMEN
In response to a call for the global eradication of malaria, drug discovery has recently been extended to identify compounds that prevent the onward transmission of the parasite, which is mediated by Plasmodium falciparum stage V gametocytes. Lately, metabolic activity has been used in vitro as a surrogate for gametocyte viability; however, as gametocytes remain relatively quiescent at this stage, their ability to undergo onward development (gamete formation) may be a better measure of their functional viability. During gamete formation, female gametocytes undergo profound morphological changes and express translationally repressed mRNA. By assessing female gamete cell surface expression of one such repressed protein, Pfs25, as the readout for female gametocyte functional viability, we developed an imaging-based high-throughput screening (HTS) assay to identify transmission-blocking compounds. This assay, designated the P. falciparum female gametocyte activation assay (FGAA), was scaled up to a high-throughput format (Z' factor, 0.7 ± 0.1) and subsequently validated using a selection of 50 known antimalarials from diverse chemical families. Only a few of these agents showed submicromolar 50% inhibitory concentrations in the assay: thiostrepton, methylene blue, and some endoperoxides. To determine the best conditions for HTS, a robustness test was performed with a selection of the GlaxoSmithKline Tres Cantos Antimalarial Set (TCAMS) and the final screening conditions for this library were determined to be a 2 µM concentration and 48 h of incubation with gametocytes. The P. falciparum FGAA has been proven to be a robust HTS assay faithful to Plasmodium transmission-stage cell biology, and it is an innovative useful tool for antimalarial drug discovery which aims to identify new molecules with transmission-blocking potential.
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Antimaláricos/farmacología , Plasmodium falciparum/efectos de los fármacos , Animales , Femenino , Ensayos Analíticos de Alto Rendimiento , Concentración 50 Inhibidora , Azul de Metileno/farmacología , Plasmodium falciparum/genética , ARN Mensajero/genética , Tioestreptona/farmacologíaRESUMEN
It is the mature gametocytes of Plasmodium that are solely responsible for parasite transmission from the mammalian host to the mosquito. They are therefore a logical target for transmission-blocking antimalarial interventions, which aim to break the cycle of reinfection and reduce the prevalence of malaria cases. Gametocytes, however, are not a homogeneous cell population. They are sexually dimorphic, and both males and females are required for parasite transmission. Using two bioassays, we explored the effects of 20 antimalarials on the functional viability of both male and female mature gametocytes of Plasmodium falciparum. We show that mature male gametocytes (as reported by their ability to produce male gametes, i.e., to exflagellate) are sensitive to antifolates, some endoperoxides, methylene blue, and thiostrepton, with submicromolar 50% inhibitory concentrations (IC50s), whereas female gametocytes (as reported by their ability to activate and form gametes expressing the marker Pfs25) are much less sensitive to antimalarial intervention, with only methylene blue and thiostrepton showing any significant activity. These findings show firstly that the antimalarial responses of male and female gametocytes differ and secondly that the mature male gametocyte should be considered a more vulnerable target than the female gametocyte for transmission-blocking drugs. Given the female-biased sex ratio of Plasmodium falciparum (â¼3 to 5 females:1 male), current gametocyte assays without a sex-specific readout are unlikely to identify male-targeted compounds and prioritize them for further development. Both assays reported here are being scaled up to at least medium throughput and will permit identification of key transmission-blocking molecules that have been overlooked by other screening campaigns.
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Antimaláricos/farmacología , Plasmodium falciparum/efectos de los fármacos , Antagonistas del Ácido Fólico/farmacología , Malaria Falciparum/tratamiento farmacológico , Azul de Metileno/farmacología , Plasmodium falciparum/fisiología , Tioestreptona/farmacologíaRESUMEN
The production of fully functional human red cells in vitro from haematopoietic stem cells (hHSCs) has been successfully achieved. Recently, the use of hHSCs from cord blood represented a major improvement to develop the continuous culture system for Plasmodium vivax. Here, we demonstrated that CD34⺠hHSCs from peripheral blood and bone marrow can be expanded and differentiated to reticulocytes using a novel stromal cell. Moreover, these reticulocytes and mature red blood cells express surface markers for entrance of malaria parasites contain adult haemoglobin and are also permissive to invasion by P. vivax and Plasmodium falciparum parasites.
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Antígenos CD34/aislamiento & purificación , Eritrocitos/parasitología , Células Madre Hematopoyéticas/parasitología , Malaria Vivax , Malaria/sangre , Plasmodium falciparum , Diferenciación Celular , Técnicas de Cocultivo/métodos , Humanos , Reticulocitos/citología , Reticulocitos/parasitologíaRESUMEN
Malaria is one of the deadliest infectious diseases in the world, with the eukaryotic parasite Plasmodium falciparum causing the most severe form of the disease. Discovery of new classes of antimalarial drugs has become an urgent task to counteract the increasing problem of drug resistance. Screening directly for compounds able to inhibit parasite growth in vitro is one of the main approaches the malaria research community is now pursuing for the identification of novel antimalarial drug leads. Very recently, thousands of compounds with potent activity against the parasite P. falciparum have been identified and information about their molecular descriptors, antiplasmodial potency, and cytotoxicity is publicly available. Now the challenges are how to identify the most promising chemotypes for further development and how best to progress these compounds through a lead optimization program to generate antimalarial drug candidates. We report here the first chemical series to be characterized from one of those screenings, a completely novel chemical class with the generic name cyclopropyl carboxamides that has never before been described as having antimalarial or other pharmacological activities. Cyclopropyl carboxamides are potent inhibitors of drug-sensitive and -resistant strains of P. falciparum in vitro and show in vivo oral efficacy in malaria mouse models. In the present work, we describe the biological characterization of this chemical family, showing that inhibition of their still unknown target has very favorable pharmacological consequences but the compounds themselves seem to select for resistance at a high frequency.
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Amidas , Antimaláricos , Malaria Falciparum/tratamiento farmacológico , Plasmodium falciparum/efectos de los fármacos , Amidas/química , Amidas/farmacología , Amidas/uso terapéutico , Amidas/toxicidad , Animales , Antimaláricos/química , Antimaláricos/farmacología , Antimaláricos/uso terapéutico , Antimaláricos/toxicidad , Línea Celular , Eritrocitos/parasitología , Femenino , Humanos , Malaria Falciparum/parasitología , Ratones , Ratones Endogámicos NOD , Ratones SCID , Pruebas de Sensibilidad Parasitaria , Plasmodium falciparum/crecimiento & desarrollo , Relación Estructura-Actividad , Resultado del TratamientoRESUMEN
Antimalarial 4-pyridones are a novel class of inhibitors of the plasmodial mitochondrial electron transport chain targeting Cytochrome bc1 (complex III). In general, the most potent 4-pyridones are lipophilic molecules with poor solubility in aqueous media and low oral bioavailability in pre-clinical species from the solid dosage form. The strategy of introducing polar hydroxymethyl groups has enabled us to maintain the high levels of antimalarial potency observed for other more lipophilic analogues whilst improving the solubility and the oral bioavailability in pre-clinical species.
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Antimaláricos/química , Antimaláricos/farmacología , Plasmodium falciparum/efectos de los fármacos , Piridonas/química , Piridonas/farmacología , Animales , Antimaláricos/síntesis química , Química Física , Cristalografía por Rayos X , Perros , Relación Dosis-Respuesta a Droga , Concentración de Iones de Hidrógeno , Ratones , Modelos Moleculares , Estructura Molecular , Pruebas de Sensibilidad Parasitaria , Piridonas/síntesis química , Solubilidad , EstereoisomerismoRESUMEN
New antimalarial therapeutics are needed to ensure that malaria cases continue to be driven down, as both emerging parasite resistance to frontline chemotherapies and mosquito resistance to current insecticides threaten control programmes. Plasmodium, the apicomplexan parasite responsible for malaria, causes disease pathology through repeated cycles of invasion and replication within host erythrocytes (the asexual cycle). Antimalarial drugs primarily target this cycle, seeking to reduce parasite burden within the host as fast as possible and to supress recrudescence for as long as possible. Intense phenotypic drug screening efforts have identified a number of promising new antimalarial molecules. Particularly important is the identification of compounds with new modes of action within the parasite to combat existing drug resistance and suitable for formulation of efficacious combination therapies. Here we detail the antimalarial properties of DDD01034957-a novel antimalarial molecule which is fast-acting and potent against drug resistant strains in vitro, shows activity in vivo, and possesses a resistance mechanism linked to the membrane transporter PfABCI3. These data support further medicinal chemistry lead-optimization of DDD01034957 as a novel antimalarial chemical class and provide new insights to further reduce in vivo metabolic clearance.
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Antimaláricos/farmacología , Resistencia a Medicamentos/efectos de los fármacos , Malaria/tratamiento farmacológico , Plasmodium falciparum/efectos de los fármacos , Animales , Antimaláricos/química , Eritrocitos/parasitología , Interacciones Huésped-Parásitos/efectos de los fármacos , Humanos , Concentración 50 Inhibidora , Malaria/parasitología , Ratones , Estructura Molecular , Plasmodium/efectos de los fármacos , Plasmodium/parasitología , Plasmodium berghei/efectos de los fármacos , Plasmodium berghei/parasitología , Plasmodium falciparum/fisiología , Especificidad de la EspecieRESUMEN
BACKGROUND AND PURPOSE: Efficacy of current antimalarial treatments is declining as a result of increasing antimalarial drug resistance, so new and potent antimalarial drugs are urgently needed. Azithromycin, an azalide antibiotic, was found useful in malaria therapy, but its efficacy in humans is low. EXPERIMENTAL APPROACH: Four compounds belonging to structurally different azalide classes were tested and their activities compared to azithromycin and chloroquine. in vitro evaluation included testing against sensitive and resistant Plasmodium falciparum, cytotoxicity against HepG2 cells, accumulation and retention in human erythrocytes, antibacterial activity, and mode of action studies (delayed death phenotype and haem polymerization). in vivo assessment enabled determination of pharmacokinetic profiles in mice, rats, dogs, and monkeys and in vivo efficacy in a humanized mouse model. KEY RESULTS: Novel fast-acting azalides were highly active in vitro against P. falciparum strains exhibiting various resistance patterns, including chloroquine-resistant strains. Excellent antimalarial activity was confirmed in a P. falciparum murine model by strong inhibition of haemozoin-containing trophozoites and quick clearance of parasites from the blood. Pharmacokinetic analysis revealed that compounds are metabolically stable and have moderate oral bioavailability, long half-lives, low clearance, and substantial exposures, with blood cells as the preferred compartment, especially infected erythrocytes. Fast anti-plasmodial action is achieved by the high accumulation into infected erythrocytes and interference with parasite haem polymerization, a mode of action different from slow-acting azithromycin. CONCLUSION AND IMPLICATIONS: The hybrid derivatives described here represent excellent antimalarial drug candidates with the potential for clinical use in malaria therapy.
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Antimaláricos , Malaria , Animales , Antimaláricos/farmacología , Antimaláricos/uso terapéutico , Azitromicina/farmacología , Azitromicina/uso terapéutico , Cloroquina/farmacología , Cloroquina/uso terapéutico , Perros , Malaria/tratamiento farmacológico , Ratones , Plasmodium falciparum , RatasRESUMEN
A series of diaryl ether substituted 4-pyridones have been identified as having potent antimalarial activity superior to that of chloroquine against Plasmodium falciparum in vitro and murine Plasmodium yoelii in vivo. These were derived from the anticoccidial drug clopidol through a systematic study of the effects of varying the side chain on activity. Relative to clopidol the most active compounds show >500-fold improvement in IC50 for inhibition of P. falciparum in vitro and about 100-fold improvement with respect to ED50 against P. yoelii in mice. These compounds have been shown elsewhere to act selectively by inhibition of mitochondrial electron transport at the cytochrome bc1 complex.
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Antimaláricos/síntesis química , Malaria/tratamiento farmacológico , Plasmodium falciparum/efectos de los fármacos , Plasmodium yoelii , Piridonas/síntesis química , Animales , Antimaláricos/química , Antimaláricos/farmacología , Ratones , Pruebas de Sensibilidad Parasitaria , Piridonas/química , Piridonas/farmacología , Relación Estructura-ActividadRESUMEN
BACKGROUND: In vitro cultivation of Plasmodium falciparum is usually carried out through the continuous preservation of infected erythrocytes deposited in static thin layers of settled haematocrit. This technique, called the candle-jar method, was first achieved by Trager and Jensen in 1976 and has undergone slight modifications since then. However, no systematic studies concerning the geometry of the haematocrit layer have been carried out. In this work, a thorough investigation of the effects of the geometric culturing conditions on the parasite's development is presented. METHODS: Several experimental trials exploring different settings have been carried out, covering haematocrit layer depths that ranged from 6 mm to 3 mm and separation between the walls of the culturing device that ranged from 7.5 mm to 9 mm. The obtained results have been analysed and compared to different system-level models and to an Individual-Based Model. CONCLUSION: In line with the results, a mechanism governing the propagation of the infection which limits it to the vicinity of the interface between the haematocrit layer and the culture medium is deduced, and the most appropriate configurations are proposed for further experimental assays.
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Técnicas de Cultivo de Célula , Eritrocitos/parasitología , Plasmodium falciparum/crecimiento & desarrollo , AnimalesRESUMEN
Spread of parasite resistance to artemisinin threatens current frontline antimalarial therapies, highlighting the need for new drugs with alternative modes of action. Since only 0.2-1% of asexual parasites differentiate into sexual, transmission-competent forms, targeting this natural bottleneck provides a tangible route to interrupt disease transmission and mitigate resistance selection. Here we present a high-throughput screen of gametogenesis against a ~70,000 compound diversity library, identifying seventeen drug-like molecules that target transmission. Hit molecules possess varied activity profiles including male-specific, dual acting male-female and dual-asexual-sexual, with one promising N-((4-hydroxychroman-4-yl)methyl)-sulphonamide scaffold found to have sub-micromolar activity in vitro and in vivo efficacy. Development of leads with modes of action focussed on the sexual stages of malaria parasite development provide a previously unexplored base from which future therapeutics can be developed, capable of preventing parasite transmission through the population.
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Antimaláricos/análisis , Evaluación Preclínica de Medicamentos , Ensayos Analíticos de Alto Rendimiento/métodos , Malaria/parasitología , Malaria/transmisión , Parásitos/fisiología , Animales , Antimaláricos/química , Antimaláricos/farmacología , Conducta Alimentaria , Femenino , Gametogénesis/efectos de los fármacos , Células Hep G2 , Humanos , Masculino , Ratones , Parásitos/efectos de los fármacos , Fenotipo , Reproducibilidad de los Resultados , Relación Estructura-ActividadRESUMEN
Malaria is still one of the most prevalent parasitic infections in the world, with half of the world's population at risk for malaria. The effectiveness of current antimalarial therapies, even that of the most recent class of antimalarial drugs (artemisinin-combination therapies, ACTs), is under continuous threat by the spread of resistant Plasmodium strains. As a consequence, there is still an urgent requirement for new antimalarial drugs. We previously reported the identification of 4(1 H)-pyridones as a novel series with potent antimalarial activities. The low solubility was identified as an issue to address. In this paper, we describe the synthesis and biological evaluation of 4(1 H)-pyridones with potent antimalarial activities in vitro and in vivo and improved pharmacokinetic profiles. Their main structural novelties are the presence of polar moieties, such as hydroxyl groups, and the replacement of the lipophilic phenyl rings with pyridines on their lipophilic side chains.
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Antimaláricos/farmacología , Piridonas/farmacología , Animales , Antimaláricos/síntesis química , Antimaláricos/química , Antimaláricos/farmacocinética , Femenino , Ratones , Estructura Molecular , Pruebas de Sensibilidad Parasitaria , Plasmodium falciparum/efectos de los fármacos , Plasmodium yoelii/efectos de los fármacos , Piridonas/síntesis química , Piridonas/química , Piridonas/farmacocinética , Relación Estructura-ActividadRESUMEN
Plasmodium falciparum stage V gametocytes are responsible for parasite transmission, and drugs targeting this stage are needed to support malaria elimination. We here screen the Tres Cantos Antimalarial Set (TCAMS) using the previously developed P. falciparum female gametocyte activation assay (Pf FGAA), which assesses stage V female gametocyte viability and functionality using Pfs25 expression. We identify over 400 compounds with activities <2 µM, chemically classified into 57 clusters and 33 singletons. Up to 68% of the hits are chemotypes described for the first time as late-stage gametocyte-targeting molecules. In addition, the biological profile of 90 compounds representing the chemical diversity is assessed. We confirm in vitro transmission-blocking activity of four of the six selected molecules belonging to three distinct scaffold clusters. Overall, this TCAMS gametocyte screen provides 276 promising antimalarial molecules with dual asexual/sexual activity, representing starting points for target identification and candidate selection.
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Antimaláricos/farmacología , Evaluación Preclínica de Medicamentos , Células Germinativas/metabolismo , Adenosina Trifosfato/metabolismo , Animales , Antimaláricos/química , Antimaláricos/farmacocinética , Antimaláricos/uso terapéutico , Modelos Animales de Enfermedad , Femenino , Flagelos/metabolismo , Células Hep G2 , Humanos , Malaria Falciparum/tratamiento farmacológico , Malaria Falciparum/parasitología , Plasmodium berghei/efectos de los fármacos , Plasmodium falciparum/efectos de los fármacos , Reproducibilidad de los ResultadosRESUMEN
K13 gene mutations are a primary marker of artemisinin resistance in Plasmodium falciparum malaria that threatens the long-term clinical utility of artemisinin-based combination therapies, the cornerstone of modern day malaria treatment. Here we describe a multinational drug discovery programme that has delivered a synthetic tetraoxane-based molecule, E209, which meets key requirements of the Medicines for Malaria Venture drug candidate profiles. E209 has potent nanomolar inhibitory activity against multiple strains of P. falciparum and P. vivax in vitro, is efficacious against P. falciparum in in vivo rodent models, produces parasite reduction ratios equivalent to dihydroartemisinin and has pharmacokinetic and pharmacodynamic characteristics compatible with a single-dose cure. In vitro studies with transgenic parasites expressing variant forms of K13 show no cross-resistance with the C580Y mutation, the primary variant observed in Southeast Asia. E209 is a superior next generation endoperoxide with combined pharmacokinetic and pharmacodynamic features that overcome the liabilities of artemisinin derivatives.